The present invention is directed to exposure apparatuses. More specifically, the present invention is directed to a support assembly for an exposure apparatus and a method for making a support assembly for an exposure apparatus.
Exposure apparatuses are commonly used to transfer images from a reticle onto a semiconductor wafer during semiconductor processing. A typical exposure apparatus includes a support assembly, a measurement system, a plurality of control lines, a control system, an illumination source, a lens assembly, a reticle stage for retaining a reticle, and a wafer stage for retaining a semiconductor wafer.
The support assembly typically supports the measurement system, the illumination source, the reticle stage, the lens assembly, and the wafer stage above the ground. The measurement system monitors the positions of the stages. The control lines carry an electrical current between the components of the exposure apparatus. The wafer stage includes one or more motors to precisely position the wafer relative to the lens assembly. Similarly, the reticle stage includes one or more motors to precisely position the reticle relative to the lens assembly.
The size of the images transferred onto the wafer from the reticle is extremely small. Accordingly, the precise relative positioning of the wafer and the reticle is critical to the manufacture of high density, semiconductor wafers.
Unfortunately, mechanical vibrations and deformations in the support assembly of the exposure apparatus can influence the accuracy of the exposure apparatus. For example, the motors utilized to move the stages generate reaction forces that vibrate and deform the support assembly of the exposure apparatus. Additionally, the control lines carry vibration from the control system and other items that the control lines touch on the way to the exposure apparatus that also vibrate the exposure apparatus and the support assembly.
The vibrations and deformations in the support assembly can move the stages and the lens assembly out of precise relative alignment. Further, the vibrations and deformations in the support assembly can cause the measurement system to improperly measure the relative positions of the stages. As a result thereof, the accuracy of the exposure apparatus and the quality of the integrated circuits formed on the wafer can be compromised.
One attempt to solve this problem involves the use of a support assembly having a main frame and a reaction frame. The main frame is used to support most of the components of the exposure apparatus above the ground, while the reaction frame is used to transfer the reaction forces from the motors of the stages to the ground.
Unfortunately, with this design, the reaction frame occupies space in the exposure apparatus that was previously available to other components of the exposure apparatus. As a result thereof, the exposure apparatus will be required to have a larger footprint in order to accommodate the reaction frame. Further, access to the reaction frame can be limited. Thus, it can be difficult to connect each significantly vibrating component to the reaction frame. Moreover, the reaction frame limits access to the other components of the exposure apparatus.
In light of the above, it is an object of the present invention to provide an improved support assembly for an exposure apparatus. Another object is to provide a support assembly that reduces the influence of vibration from the motors of the exposure apparatus on the position of the stages, the lens assembly, and the measurement system. Still another object is to provide a support assembly having a relatively small footprint. Yet another object is to provide a support assembly having a reaction frame that is easily accessible. Another object is to provide a support assembly that is relatively inexpensive to manufacture. Yet another object of the present invention is to provide a support assembly that transfers the vibration from the motors and the illumination source to the ground so that the reticle stage and the wafer stage can be precisely positioned. Another object is to provide an exposure apparatus capable of manufacturing precision devices, such as high density, semiconductor wafers.
The present invention is directed to a support assembly that satisfies these needs. The support assembly is designed to support a stage assembly above a mounting base. The stage assembly includes a first component and a second component. The support assembly includes an outer frame that supports the first component and an inner frame that supports the second component. The support assembly and stage assembly are particularly useful with an exposure apparatus for transferring an image from a reticle onto a device.
Uniquely, a portion of the inner frame is positioned within a portion of the outer frame. As a result of this design, both frames can effectively be mounted at the same mounting locations to the mounting base. This minimizes the impact of vibration of the mounting base influencing the support assembly. Further, the overall space taken up by the frames is minimized. This allows the support assembly to have a smaller footprint and allows the components of the stage assembly and/or the exposure apparatus to be more accessible.
As used herein, the term xe2x80x9cnoisy componentsxe2x80x9d shall mean and include any component of the stage assembly and/or the exposure apparatus that generates significant vibration, reaction forces, and resonant forces. As used herein, the term xe2x80x9cquiet componentsxe2x80x9d shall mean and include any component of the stage assembly and/or the exposure apparatus that does not generate significant vibration, reaction forces, and resonant forces. Importantly, the noisy components typically generate significantly more vibration, reaction forces, and resonant forces than the quiet components.
Preferably, one of the frames is utilized as a reaction frame while the other frame is utilized as a quiet frame. The reaction frame supports and secures the noisy components to the mounting base. Alternately, the quiet frame supports and secures the quiet components to the mounting base. With this design, the reaction forces from the noisy components can be easily transferred to the mounting base and isolated from the quiet components. This allows for more accurate positioning of the reticle and the device, and the manufacture of higher density, semiconductor wafers.
In one of the embodiments provided herein, (i) the outer frame includes a first side outer tube, a second side outer tube, and a third side outer tube and (ii) the inner frame includes a first side inner tube, a second side inner tube, and a third side inner tube. Further, in this embodiment, (i) the first side inner tube is positioned within the first side outer tube, (ii) the second side inner tube is positioned within the second side outer tube, and (iii) the third side inner tube is positioned within the third side outer tube.
Additionally, the outer frame includes an outer base, and the inner frame includes an inner base that is positioned within the outer base. More specifically, the outer base includes a first base outer tube, a second base outer tube, and a third base outer tube. The inner base includes a first base inner tube, a second base inner tube, and a third base inner tube. As provided herein, (i) the first base inner tube is positioned within the first base outer tube, (ii) the second base inner tube is positioned within the second base outer tube, and (iii) the third base inner tube is positioned within the third base outer tube.
In another embodiment of the present invention, the support assembly includes a first tube, a constraining tube, and a dampener. In this embodiment, the constraining tube is positioned within the first tube and the dampener is positioned between and is affixed to both the first tube and the constraining tube.
The present invention is also directed to a method for making a support assembly, a method for making an exposure apparatus, a method for making a device, and a method for manufacturing a wafer.